An outbreak of listeria that has been linked to three deaths and forced a popular ice cream from store shelves across the central US may have begun as far back as 2010, according to experts.

Listeria found in products from Texas-based Blue Bell Creameries has been linked to 10 illnesses – leading to three deaths – in Oklahoma, Arizona, Texas and Kansas. In response the company has recalled all of its products and is overhauling its cleaning procedures.

“We’re committed to doing the 100% right thing, and the best way to do that is to take all of our products off the market until we can be confident that they are all safe,” Paul Kruse, Blue Bell CEO and president, said in a statement. “We want enjoying our ice cream to be a source of joy and pleasure, never a cause for concern, so we are committed to getting this right.”

The outbreak shows a problem with our food surveillance system, said Mansour Samadpour, president and CEO of IEH Laboratories and Consulting Group, a food safety consulting lab. The problem, he says, is industry-wide, not limited to Blue Bell Creameries.

“Many of these outbreaks are detected by chance events,” he said.

In the case of Blue Bell, that event was when five patients who contracted listeria at a Kansas hospital were found to have consumed milkshakes made with Blue Bell ice cream. By testing additional Blue Bell products, collecting different strains of listeria and running them through a national database of previous listeria cases, investigators were able to link the products to past cases in other states.

“As new strains are identified out of the [Blue Bell] products, we will go back to the database and see if there are human matches,” Karen Neil, a medical epidemiologist with the CDC’s Division of Foodborne, Waterborne and Environmental Diseases, told the Dallas Morning News. “You can never predict how big an outbreak is going to be.”

The CDC has been collecting listeriosis samples from people who were affected but whose illness was never linked to a specific product since 2004. So far, the Blue Bell outbreak has been linked to cases as far back as 2010. The length and the span of the outbreak was news to the company.

“That was a surprise to us, yeah,” Joe Robertson, Blue Bell’s relations manager, told National Public Radio. “You’re going along; you’re not having a problem. And we hadn’t had a recall or a problem in our 108-year history. But to know that anyone may have gotten sick after eating our product – that’s heartbreaking to us.”

Outbreaks that last this long are more common than one might think, said Samadpour. They occur whenever the investigators cannot connect the dots and are not able to find the source of the outbreak, which means that the contaminated product continues to be sold.

“By the time people are sick, it’s too late,” he said. Companies should be diligent in their sampling and testing. “If you are producing food, let’s not assume that the food is safe until proven otherwise. Let’s just assume that the food is not safe until proven otherwise.”

That is exactly what Blue Bell said it will do going forward. Prior to the news of the outbreak, Blue Bell regularly tested its product. Now, it will test every single batch before it ships.

“Blue Bell is implementing a procedure called ‘test and hold’ for all products made at all of its manufacturing facilities,” the company said in a statement. “This means that all products will be tested first and held for release to the market only after the tests show they are safe. The Broken Arrow facility will remain closed as Blue Bell continues to investigate.”

The company is also expanding its cleaning and sanitation system and its employee training, and is sending daily samples to a microbiology laboratory for testing. Additionally, its system of swabbing and testing of the plant is expanding by 800% to include more surfaces.